The heart has been opened to display the aortic cusps; these show fenestration at several points.
Classically the fenestrations appear adjacent to the commissures and are asymptomatic, because
they are usually above the level of apposition; incompetence will occur if there is associated
dilatation of the valve ring or if the fenestration ruptures to the free edge of the valve.
Ref. American Journal of Medicine 1958; 24:549.